Fig. 1.

Bone marrow macrophage-derived extracellular vesicles from obese mice induce bone deterioration in lean mice.

(A) Representative picture of BMM-EVs (left), scale bar: 100 nm; representative western blotting images of CD9, Tsg101, CD63, and Calnexin in cell lysis of bone marrow macrophage and BMM-EVs (right). (B) Schematic diagram of lean mice with lean/obese BMM-EVs intervention. (C) Representative μCT images of lean mice with lean/obese BMM-EVs intervention. n = 5 per group. (D–G) Quantitative μCT analysis of BV/TV, Tb. N, Tb. Th, and Tb. Sp from lean mice with lean/obese BMM-EV intervention. n = 5 per group. (H) Representative images of osteocalcin immunohistochemical staining (H, top). Red arrows mark osteoblasts. Scale bar: 50 μm; representative images of H&E staining (H, middle), and Trap staining (H, bottom) in distal femora. Scale bar: 100 μm. (I–K) Quantification of the number of osteocalcin-positive osteoblasts (I) and number and area of adipocytes (J–K). (L) Quantification of osteoclast number in distal femora from lean mice with lean/obese BMM-EV intervention. (M) BMM-EVs were taken up by SSPCs. Red fluorescence represents PKH26 marked extracellular vesicles; green fluorescence represents phalloidin labeled cytoskeleton, and blue fluorescence indicates nuclei. Scale bar: 2.5 μm. (N) Representative images of Alizarin red staining of lean BMM-EV and obese BMM-EV-treated SSPCs (N, top); representative images of oil red O staining of lean BMM-EV and obese BMM-EV-treated SSPCs (N, bottom). n = 3 per group. Scale bar: 100 μm. (O–P) qRT-PCR analysis of the relative expression levels of osteogenic genes (O) and adipogenic genes (P) in lean BMM-EV and obese BMM-EV-treated SSPCs cultured in osteogenesis and/or adipogenesis induction medium. Data is shown as mean ± SD. *P < 0.05, **P < 0.01, ns, no significant. (Welch's test is used in Fig. 1G, and student t-test is used in others).